This invention relates generally to testing devices. More particularly, the present invention is directed to a device and method for testing alternators.
Alternators are typically tested outside of the motor vehicles in which they are utilized to charge the batteries and supply power to other electrical loads in motor vehicles. Many testing devices and methods for utilize a motor to drive the alternator during testing. However, improvements can be made to alternator testing systems that produce a current output from the alternator.
The output current of the alternator during testing with these devices is limited to the amount of power available from the power source to which the motor is connected.
Typically, the motor receives its power from a one hundred twenty volt alternating current (AC) receptacle, which causes the alternator to output about five to ten amperes (amps) of AC current, rather than an approximate one hundred amps of AC current that the alternator would output if the alternator was operating at full capacity within a motor vehicle.
An alternator contains three coils, and each of the three coils generates an AC voltage. A pair of diodes are coupled to the AC voltage output of each coil. The diodes allow current to flow in one direction and prevent a battery from discharging by stopping the flow of current to ground. The diodes also convert the AC voltage to direct current (DC) voltage. Notwithstanding the use of the diodes, a slight amount of ripple voltage usually remains.
If the diodes are defective, the amount of ripple voltage that manifests at the terminal of the alternator, which would be connected to a battery of a motor vehicle, significantly increases. During testing, therefore the alternator will generate a low output current of the order of five to fifteen amps, which is still well below the alternator""s full capacity current output. Thus, the amount of ripple voltage, when occurring, will also be relatively small. Accordingly, the ability to detect malfunctioning alternator diodes may be difficult.
Thus, it would also be desirable to provide a device and method for testing an alternator that allows an alternator under test to output an amount of current at or near its full current output capacity. It would also be desirable to provide a device and method for detecting malfunctioning alternator diodes.
In one aspect of the invention an alternator testing system is provided that includes a current source, a motor and a drive belt. The drive belt couples the motor to an alternator that operates outside of a motor vehicle, and the current source and the motor enable diodes of the alternator to output a current that is not limited by input power to the motor.
In another aspect of the invention, an alternator testing system is provided in which the current source is a switching power supply.
In another aspect of the invention, an alternator testing system is provided in which the current source is a transformer.
In another aspect of the invention, an alternator testing system is provided in which the current source outputs approximately eighty amps of current.
In another aspect of the invention, an alternator testing system is provided in which the input power to the motor is a 120 volt, AC power source.
In another aspect of the invention, an alternator testing system is provided in which the motor causes the alternator to output between approximately five to fifteen amps.
In another aspect of the invention, an alternator testing system is provided in which the motor and the current source cause the alternator to output between 85 to 100 amps.
In another aspect of the invention, an alternator testing system is provided in which a resistor is positioned between a first output terminal of the alternator and the current source.
In another aspect of the invention, an alternator testing system is provided in which the resistor is utilized to establish an excitation voltage for the alternator.
In another aspect of the invention, an alternator testing system is provided in which the output current through the resistor is measured.
In another aspect of the invention, an alternator testing system is provided in which a resistor is positioned between the first output terminal of the alternator and ground.
In another aspect of the invention, an alternator testing system is provided in which a current sensor, which generates an output voltage is positioned in series with the resistor.
In another aspect of the invention, an alternator testing system is provided in which an analog-to-digital (A/D) converter converts the voltage output from the current sensor to a digital signal.
In another aspect of the invention, an alternator testing system is provided in which an output voltage from the alternator is fed into the A/D converter.
In another aspect of the invention, an alternator testing system is provided in which a testing device is provided that has software which analyzes the digital signal and identifies irregularities in performance by the diodes.
In yet another aspect of the present invention, a method for testing an alternator is provided that includes, supplying a first current to an alternator that operates independently from a motor vehicle, utilizing an independent current source, and generating a second current from the alternator utilizing a motor, wherein the first current and the second current enable diodes of the alternator to output a current that is not limited by input power to the motor.
Further, in another aspect of the present invention, an alternator testing system is provided that includes, a means for supplying a current to an alternator, a means for driving an alternator, and a means for coupling the driving means to the alternator. The current supplying means and the driving means enable diodes of the alternator to output a current that is not limited by input power to the motor.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto.